Have you tried Tracks from, or the whole "Midnight Soul Dive" compilation by Aleph Zero?
This is still my number one choice for Chillout that is introspective, rather dark and highly emotional.
It's not exactly like the tracks you've been successful with, but you should give it a try...
You probably have tried Hallucinogen in Dub, but if not, give it a shot. I cant decide whether i should consider it as really dark, but it sure is the most emotional psychedelic Dub Album out there...